| 摘要 |
PROBLEM TO BE SOLVED: To provide a motor device which allows for accurate reversal operation of a worm wheel within a narrow angular range while suppressing manufacturing cost increase.SOLUTION: A sensor magnet 53 is provided at a position offset from the center of rotation C of a worm wheel 52. An MR sensor 23b is provided at a position facing a sensor magnet 53 as the worm wheel 52 rotates relatively, within a projection range thereof in the axial direction of an output shaft 22. The MR sensor 23b can thereby be located at a position where the line of magnetic flux of the sensor magnet 53 is formed arcuately, as the worm wheel 52 rotates relatively. Within a narrow angular range of rotation of the worm wheel 52 less than 180° (within a range of 90° in the embodiment), the direction of line of magnetic flux crossing the MR sensor 23b can be changed from forward direction to reverse direction (180° reversal). |
